The Altra Reinforced Concentric Outset System (A.R.C.O.S.) for 166 Shafts is designed to deliver unmatched durability and performance. Crafted from 7075-T6 aluminum, this system includes an insert that secures into the arrow shaft at a depth of 0.875 inches, while the outsert threads directly onto the insert, encapsulating the leading end of the arrow by 0.43 inches. Pre-installed rubber O-rings help lock the outsert in place, reducing vibration and enhancing concentricity for a more precise arrow setup and improved downrange accuracy. Available in four spine sizes, the A.R.C.O.S. system is perfect for those seeking optimal fit and performance.